Calorimetric and Dielectric Investigations of Epoxy-Based Nanocomposites with Halloysite Nanotubes as Nanofillers

Omar, Hassan Aboubakr; Smales, Glen J.; Henning, Sven; Li, Zhi; Wang, De‐Yi; Schönhals, Andreas; Szymoniak, Paulina

doi:10.3390/polym13101634

Cited by 17 publications

(3 citation statements)

References 82 publications

(118 reference statements)

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“…However, at the higher gold concentration (75 mM), the shear-thinning index falls in the range of most thermosensitive chitosan-based hydrogels [ 60 ]. Therefore, the network of Au75@OBC nanofibers should be harder to break, revealing the role of fillers in the formation of polymer corona around the ultrafine particles that hinder flow [ 61 ]. It is worth mentioning that cellulose nanofibers could be oriented under shear forces; hence, the shear-thinning behavior of the hydrogels could be intensified with a decrease in the Newtonian-behavior region.…”

Section: Resultsmentioning

confidence: 99%

An Electroconductive, Thermosensitive, and Injectable Chitosan/Pluronic/Gold-Decorated Cellulose Nanofiber Hydrogel as an Efficient Carrier for Regeneration of Cardiac Tissue

et al. 2022

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Myocardial infarction is a major cause of death worldwide and remains a social and healthcare burden. Injectable hydrogels with the ability to locally deliver drugs or cells to the damaged area can revolutionize the treatment of heart diseases. Herein, we formulate a thermo-responsive and injectable hydrogel based on conjugated chitosan/poloxamers for cardiac repair. To tailor the mechanical properties and electrical signal transmission, gold nanoparticles (AuNPs) with an average diameter of 50 nm were physically bonded to oxidized bacterial nanocellulose fibers (OBC) and added to the thermosensitive hydrogel at the ratio of 1% w/v. The prepared hydrogels have a porous structure with open pore channels in the range of 50–200 µm. Shear rate sweep measurements demonstrate a reversible phase transition from sol to gel with increasing temperature and a gelation time of 5 min. The hydrogels show a shear-thinning behavior with a shear modulus ranging from 1 to 12 kPa dependent on gold concentration. Electrical conductivity studies reveal that the conductance of the polymer matrix is 6 × 10−2 S/m at 75 mM Au. In vitro cytocompatibility assays by H9C2 cells show high biocompatibility (cell viability of >90% after 72 h incubation) with good cell adhesion. In conclusion, the developed nanocomposite hydrogel has great potential for use as an injectable biomaterial for cardiac tissue regeneration.

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Section: Resultsmentioning

confidence: 99%

An Electroconductive, Thermosensitive, and Injectable Chitosan/Pluronic/Gold-Decorated Cellulose Nanofiber Hydrogel as an Efficient Carrier for Regeneration of Cardiac Tissue

et al. 2022

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“…Due to the small dimensions of the nanoparticles the amount of RAF can be high and determine the properties of the fiber composites to a large extent. The formalism to quantitatively estimate RAF, initially introduced by Wunderlich et al for semicrystalline polymers, was adopted for several nanocomposite systems. − Here, a three-phase model is used to describe an amorphous nanocomposite. A polymer nanocomposite is thus composed of MAF, a possible RAF, and the nanofiller.…”

Section: Resultsmentioning

confidence: 99%

Electrospun Nanocomposite Fibers of Polycarbonate- and Taurine-Modified Boehmite Nanoparticles: What Can Be Learned from Structural and Thermal Investigations?

Murillo

Szymoniak

Smales

et al. 2021

ACS Appl. Polym. Mater.

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Though the reinforcing properties of inorganic particles in thermosetting nanocomposites have been exploited, the integration of nanoparticles continues to be challenging in terms of their homogeneous distribution and their manipulation, which can contribute to occupational hazards. Due to second encapsulations of nanoparticles, electrospun nanocomposite fibers containing nanoparticles might be an alternative for overcoming these issues, as the nonwoven fibers contain nanoparticles allowing for safer manipulation. Here, the morphology and the thermal properties of electrospun polycarbonate fibers containing taurinemodified boehmite nanoparticles (BNPs) are investigated by means of small-and wide-angle X-ray scattering as well as fast scanning and temperature-modulated fast scanning calorimetry for the first time. The latter techniques allow the investigation of the thermal properties of single fibers at heating rates of up to 10 4 K s −1 keeping their structure intact. An analysis of the scattering data reveals a porous structure of the fibers. The porous structure is quantified regarding the pore volume and the pore size. A constant amount of aggregation is found even for the highly BNP-loaded fibers. Thermal analysis of the fibers reveals a rigid amorphous fraction (RAF), where it is known that the RAF determines the properties of a nanocomposite to a large extent. For the fibers, the RAF amounts up to 40 wt %, which is essentially higher compared to equally formulated PC/BNP composite cast films. The RAF, in the case of fibers, is not only due to the presence of particles in the polymer but also due to the orientation effects induced by the electrospinning process.

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“…Such behavior was not found. The accumulation of the IC-based material, together with the decrease in ∆c p , indicates the formation of a rigid amorphous fraction on the silica surface [27,62].…”

Section: Composition Dependence Of the Glass Transitionmentioning

confidence: 99%

Kinetics of the Glass Transition of Silica-Filled Styrene–Butadiene Rubber: The Effect of Resins

2022

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Resins are important for enhancing both the processability and performance of rubber. Their efficient utilization requires knowledge about their influence on the dynamic glass transition and their miscibility behavior in the specific rubber compound. The resins investigated, poly-(α-methylstyrene) (AMS) and indene-coumarone (IC), differ in molecular rigidity but have a similar aromaticity degree and glass transition temperature. Transmission electron microscopy (TEM) investigations show an accumulation of IC around the silanized silica in styrene–butadiene rubber (SBR) at high contents, while AMS does not show this effect. This higher affinity between IC and the silica surface leads to an increased compactness of the filler network, as determined by dynamic mechanical analysis (DMA). The influence of the resin content on the glass transition of the rubber compounds is evaluated in the sense of the Gordon–Taylor equation and suggests a rigid amorphous fraction for the accumulated IC. Broadband dielectric spectroscopy (BDS) and fast differential scanning calorimetry (FDSC) are applied for the characterization of the dielectric and thermal relaxations as well as for the corresponding vitrification kinetics. The cooling rate dependence of the vitrification process is combined with the thermal and dielectric relaxation time by one single Vogel–Fulcher–Tammann–Hesse equation, showing an increased fragility of the rubber containing AMS.

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Calorimetric and Dielectric Investigations of Epoxy-Based Nanocomposites with Halloysite Nanotubes as Nanofillers

Cited by 17 publications

References 82 publications

An Electroconductive, Thermosensitive, and Injectable Chitosan/Pluronic/Gold-Decorated Cellulose Nanofiber Hydrogel as an Efficient Carrier for Regeneration of Cardiac Tissue

An Electroconductive, Thermosensitive, and Injectable Chitosan/Pluronic/Gold-Decorated Cellulose Nanofiber Hydrogel as an Efficient Carrier for Regeneration of Cardiac Tissue

Electrospun Nanocomposite Fibers of Polycarbonate- and Taurine-Modified Boehmite Nanoparticles: What Can Be Learned from Structural and Thermal Investigations?

Kinetics of the Glass Transition of Silica-Filled Styrene–Butadiene Rubber: The Effect of Resins

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